In Monopolistic Competition the Costs of Less Than Optimal Production

In monopolistic competition the costs of less than optimal production may be counteracted by:

A) the gain in economic welfare that results from production differentiation
B) the fact that what is produced is sold at a price that is equal to marginal cost
C) the fact that what is produced is sold at a price that is greater than marginal cost
D) the economic profit that producers can make in the long run